A mathematical model for the uptake of ions from the soil solution

Summary A model is developed in which the uptake of ions which exist wholly in the soil solution is described in terms of their net movement towards the surfaces of roots. The ions are assumed to move either by diffusion, or in the mass flow of water towards the roots, and, given these two ways of movement, the model is based on five main assumptions. The validity of these assumptions is discussed, together with some of the model's implications, and a few experiments are suggested by which it could be tested.